Tidal hydraulic air compressor



Nov. 6, 1928.

H. M. KNIGHT TIDAL HYDRAULIC AIR COMPRESSOR 1 1 Sheets-Sheet 1 Original Filed Oct. 2.

Nov. 6,' 1928. 1,690,787

' H. M. KNIGHT TIDAL HYDRAULIC AIR COMPRESSOR Original Filed Oct. 2 4 Sheets-Sheet 2 Nov. 6, 1928.

H. M. KNIGHT TIDAL HYDRAULIC AIR COMPRESSOR Origingl Filed, Oct. '7. 1921 4 shegfls -shgei Nqv. 6, 1928.

H. M. KNIGHT TIDAL HYDRAULIC AIR COMPRESSOR Original Filed Oct. 7. 1921 4 sp n -sum '4,

i mm a? Ilill lll VEN Patented Nov. 6, 1928.

um rao STATES -PATENT oFFice.

TIDAL'HYDRAULIC AIR COMPRESSOR.

Application 'file'd October '7, 1921, Serial No. 506,006. Renewed Apri1'3, 1928.

This invention relates to hydraulic air compressors and has specific application to that type of hydraulic compressorknown as a tidal 'QOIDPIQSSOI'. I

One of the objects of this invention is to produce a tidal compressor which shall be operative on both the flood and ebb tides.

. rather than a variable head. Another object of the inventionis: to produce a'tidal compressor in which the tidal elevations shall be equalized before each tidal change. Another object of'the invention is't-o produce a tidal power plant composed oftwo inter-related parts, a tidal compressor operated under an augmentedhead induced by low pressure air exhausted in an air exp'ansionengine and an air expansion engine exhausting below atmosphere after pre heating, refrigerating and regeneration. Other objects'ofthe invention will appear from the following description andfrom the accompanying drawmgs.

The accompanying drawings, Figs. 1 to 13 inclusive illustrate the usual-and preferred embodiment of the invention but are'not to be considered as inclusive ofany and all forms in which the invention maybe embodied, nor as exclusive of forms other than that inicated. i g

I illustrate m invention by the accompanying drawings in which Fig. 1 is a plan view of my tidal compressor plant, Fig. 2 is an elevation of such a tidal compressor plant on the line 22 of Fig. 1 3 is a cross-section on the line 3-3 ofFig. 1; Fig, i is a cross-section on the line d-t ofFig. '1; Fig. 5 is a cross-section ofa supporting'pontoon on the 'line 5-5 of Fig.7; Fig. his a longitudinal section of a pontoon and its supported water elevating apparatus on the line 6-6 of Fig. 7; Fig. 7 is a horizontal section on the 'line 77 of Fig.6 ;'8 is alongitudinal section of the water elevating"means on the 'line 8-8 of'Fig. 10; Fig.9"is-a-cross section of the water'elevating means on the line 99 of Fig. 8; Fig. 10 is a horizontal section of such water elevating means on the line 1( ).-1O Fig. '81; Fig. .11 "is an elevation Referring to the drawings in which similar numbers refer to similar parts; *1, is a tidal estuary closed by a dam 2,fr'om the sea 3, and having a lock 4., in said dam.

In a fore-bay basin 5, connected with'tlie dam, islocated an initial compressor 6, having a head-piece 7, telescoping ina downtake pipe 8, connected by apassage'9, with a separation chamber 10. An up-takepipe 11, discharges'into a tail-race basin12. "Gates 13, are located on the seaward side o f' the fore-bay basin and other gatesld, are located on the estuary side'thereof. Gates 15, are located on "the seaward side of thetail-racc basin and othergates lG, arelocated on the estuary side thereof; I

A fore-bay basin 17, floats ,pontoons 18, located betweenguides 19. Posts 20, attached to the ,pontoonssupport a water-elevating apparatus 21. Supply pipes 22', have their lower ends 23, immersed in the water of. the fore-bay and their'upper ends 24, open into a vacuum chamber 25. F cot-valves 26, are located'near the lower extremities of the supply pipesand flap-valves 27,'are upon their upper ends( partition28, havinga sealed opening 29, in the bottom thereof separates the vacuum chamber from the limit chamber 30. I A float 31, traverses vertically upon the guides 32. Float arms 33, engage the float at its highest and lowest 'points'df travel. Valve-arms 34, are-attached to thefioat-arms and also to the arbor 35 of a divided auto-v matic valve'36. port 37, ope'i- 'atesto open and close communication betweena pipe 38, f freely open in the roo'f of the floatchamber anda pipe 39, regulatably open to the atmosphere,'and a'port 40 operates inalternation with the previous port to open a close communication between ajpipe 11, freely open in the roof of the float-chamber andapipe 42, freely open in'the roof ofthe vacuum chamber. A weir 43,is located inthe float chamber trapping-the sealed opening in the dividing partition betweenthe yacuu n chamber and the float-chamber. Siphon draft-tubes 14, pass tl'iroughthe end casingfl5, of the float chamber and discharge ibenea th ,a, flapvalve 46, into adischarge conduit11d7,leading toa head-piece 48, suspendedoveratelescoping section 49, supported by the pontoon and which descends into the down-take pipe 50, connected by a passage 51, with the separation chamber. An outlet 52, with its face 53, near the roof of the vacuum chamber, is protected by a flap-valve 54, and has a connection 55, with a pipe 56, leading to source of vacuum. Flood-gates 57, and pumps 58, regulate the immersion and trim of the pon toons. Grates 59, are located on the seaward side of the fore-bay basin and other gates 60, are located on the estuary side thereof.

An air supplyinain 61, leads from the separation chamber, a regulating valve 62, being located thereon, and enters a pro-heater 63.

A high-pressure main 64, leads to the initial cylinder 65, of an air engine 66. An exhaust main 67, leads from the initial cylinder to a freezer 68. A dry-air main 69, leads through an atmospheric interehanger 70, to the heat regenerator 71. A supply main 72, leads to the supplementary expansion cylinder 73. An exhaust main 74, leads from the supplementary expansion cylinder to the freezer. A low pressure exhaust main 75, leads from the freezer to the vacuum tank 7 6. A vacuum regulating valve 77, is attached tosaid vacuum tank. A vacuum pipe 78, is connected to the cylinders 79, of a vacuum pump 80. A blow-off pipe 81, connects the separation chamber with the atmosphere. A wave pro tecticn wall 82, is located seaward of the tailrace basin, having openings 83, therein. The lowest point of the water surface of the separation chamber is at 84, which is the bottom of the blow-off pipe. An elevation of the water surface within the fore-bay basin and on one side of the dam is at 85, while 86, represents the water surface on the other side of the dam and within the tail-race basin. The water surface of the discharge channel is at 87, and that of the float-chamber 88.

A hydraulic compressor is an apparatus de signed to entrain air by the passage of water under a head through a tubular head-piece, the combined air and water descending a down-take pipe to a considerable depth, be low the tail-race level, the air being gradually compressed in its descent, the air and water being discharged into a separation chamber. in which the entrained air is liberated and rises above the water surface, due to the slowing up of the stream of water in the chamber. after which separation, the water rises in an up-take column to the tail-race level. The power utilized is that represented by the amount of water and the difference in elevation between the fore-bay and the tail-race, or, in the case of a. tidal compressor,the'diiference in elevation between the surface of the water above and below the dam, and the pressure of the air in the separation chamber is that represented by the weight of the column of water whose height is the difference between the elevatlon of the water in the separation chamber and the elevation of the surface of the water in the tail-race. Such hydraulic compressors are generally installed upon streams above their tidal basins, and in locations where constant, or nearly constant rela tion exists between the elevations of the fore-bay and tail-race, respectively. But in the case of a tidal compressor this is entirely otherwise, the estuary fluctuating from the maximum elevation at flood to the minimum of ebb tide twice daily. A tidal compressor under such conditions is subjected to a con stantly varying head during both the flood and the ebb tides. It becomes necessary, due to the varying head, to wait a long time at each turn of the tide, before a sufficient fall has developed to make the operation of the compressor either possible or satisfactory, such waiting cutting down materially the effective hours of operation. As most tidal fluctuations are comparativelly small in amount, such delay, in order to secure a working head, makes the utilization of tidal powers of doubtful value, as ordinarily developed.

This invention overcomes the usual and manifest defects of ordinary tidal power development by the following means. A dam is erected across the mouth of a tidal estuary, locks being provided therein for the passage of vessels at all water stages.

By the construction of such a dam, a tidal head can be produced onboth the ebb and the flood tides, and a condition established resulting in four operative periods during a 2% hour day. But these four operative periods may be of comparatively short duration, especially where the amplitude of tidal fluctuation is slight, due to the fact that a certain period of time must be allowed in which to establish a difference between the elevations of the water on the two, sides of the barrage, sufticient to producean adequate working head. This may be as much as one-half of the tidal period, so that continuous operation may not be possible above three hours at any onetime. By my invention these difficulties are overcome, a constant working head maintained and a considerable lengthening of the o ierative period secured by use of a means for augmenting the normal head, as represented by the difference in the elevations of the water i on either side of the barrage,by elevating the water'before passage through the hydraulic compressor, r

The operation of this water elevating niieans is as follows: Connected with the dam, is a fore-bay basin. This fore-bay basin is completely enclosed by walls higher than the point of highest tide, the only means of connection therewith being through gates connecting with the estuary and with the sea,.re spectively. hen the water is higher in the estuary the gates connecting therewith are open and water enters the fore-bay therethrough, the sea-ward gates being closed, and, conversely, upon the reversal of the tide and l SQ during the flood, theseestuary gates are closed and-the sea-ward gates are opened permitting water to enter the fore-bay from the sea. Such water, so entering the fore-bay, either from the estuary or from the sea, finds its exit through the hydraulic compressor. it is thus seen thatthe fore-bay, with its com pressor mechanism, becomes the channel through which the tidal-currents ebb and flow, and, consequently that such flow in reverse direction twice daily results in four tidal power periods. The inlets of the hydraulic compressors are located within this fore-bay, extending downwardly therefrom to and through the separation chamber and upwardly through the up-take shaft to the tail-race. Thetail race is similar to the fore-bay, i

that it is a completely enclosed basin surrounded with walls sufliciently high to prevent overtopping by tides, and having gates on opposite sides thereof connecting with the sea and the estuary respectively. The operation of these gates is similar to the operation of thefore-bay-gates, except that these gates are always in reverse position, relatively, to the fore-bay gates, that is, when the estuary gates of the fore-bay are open the estuary gates ofthe tail-race are closed andthe sea.- war'd gates open, and vice versa. It ist-herefore apparent that water entering the forebay throu h the estuary gates thereof finds exit seaward through the sea-ward gates of the tail-race, after having passed through the hydrauliccompressor, and, vice versathe only passage for the escapeoitthe tidal flow both in ebb and flood being throughtl e's'aid forebay, hydraulic compressor and tail-race.

Inthe fore-bay float a multiple ofpontoons supporting a chambered structure elevated upon posts attachedtothedeck-of the 'pontoons. These pontoons are divided into compartments provided with gates for flooding and connected with pumping means,through both of which agencies the immersion and trim of thepontoons may be secured. Guide posts on the sides and reaching to-anfirm supporting attachment prevent listing or 'overturning of the pontoons and limit the height of their rise. These pontoons are provided wit-h pockets in which are located water supply pipes and the'telescope pipe from "the head-piece of the hydraulic compressor.

The chambered structure supported upon the pontoon consists, in the main,;oi an air tightbox, which at one end is connected by downwardly extending supply pipeswiththe water of the fore-bay, and at theopposite end with the head-piece of thehydra-ulic compres= sor, which said head-piece is attached to and elevated upon "the said pontoon. The supply pipes have their bottom'ext-remities completely immersed in the water of th'eSfore-bay and their upper ends discharge into thejfirst chamber of the watcrelevating apparatus, known is closed.

as the vacuum chamber. These-supply pipes are protectedlagainst a backpor return flow, by means of foot-valves located near their bottomiends, and, as an addedrprecaution, by

flapavalves .at their heads. A vacuum in the vacuum chamber causes water to rise in the supply pipeswliicli discharges into the Vacuum chambeiyand, upona change inthe pres sure inthisyacuum'chamber, the foot and flap valves :operate to close the supply pipe, preventing a return of water to the fore bay. The 'vacuum'in the vacuum chamber is produced and-maintained by means of the expansion oftheair in the air engine, which is a part ofithe power plant.

- The chambers of the water-elevating apparatus are two, the vacuum-chamber above referred to, and a float chamber adjacent to the vacuum chamber and having two means of connnunication therewith,"one through an automatic valve, the other through the Water sealed opening in thebottomot the dividing wall which separates the two chambers. In the roof o-fthe vacuum,chamber is a connection with the vacuum producing meansin con nection with theair expansion engine. The float-chamber contains afloat, held to a flxed location by guides, but free to rise and tall with the water in the float chamberythe said float operating throughfloat=arms and valvearms to open and close the ports of the automatic valve, This automatic'valve is intwo parts, one part openingand closing connection between the vacuum chamber and the float chamber and the other part opening-and closing connection between the float chamber and theatmosphere.

T he action of the water elevating apparatus is as lollows:-a vacuum having been induced in the vacuum chamber, water rises in the supply pipes from the fore-bay and overflows into the vacuum chamber. The float in the float chamber is at the bottom of its travel and the automatic valve isin such a position that a Tree Connection exists between the a'ir in the float chamber and that in the vacuum chamber, while the other half of the valve which controls connection between the float chamber and the atmosphere As the pressin'c in the vacuum chan'iber and the float chamber arethe same, tne water discharged into the vacuum chamber tl'i'rough the supply pipesenterst he float chamber through the sealed opening in the partition wall, and gradually rises, taining an equality of level in both chambers, the float rising with the rising water. When the float approaches the highest point or its travel it impinges 'upo'n the upper float arms actuatin the valve-arms which.

begin t-oclose the port in the half of the automatic valve connecting the two chambers,

and flnally completely shut-sofl all connection between them. 7 Further rise-of the float opensthe other half of the valve giving connection between the atmosphere and the roof of the float chamber. Air under atmospheric pressure immediately rushes into the float chamber, pressing downward upon the surface of the water therein. At once there is a tendency for the water vacuum chamber which is still under less than atmospheric pressure. This return into the vacuum chamber causes the water surface to rise closing the flap-valves of thesupply pipes. Its further rise shuts the flapvalve on the throat of the vacuum supply connection, and finally, the residue of air in the chamber, having no outlet is compressed to atmospheric pressure. The water supply pipes being protected at top and bottom, no water returns to the fore-bay. The iloat chamber, which like the vacuum chamher is a hermetically sealed vessel, has siphondrai t-tubes in the wall opposite the partition separating the two chambers. As soon as the atmospheric pressure begins to act upon the surface of the water in the float chamber these tubes begin to operate, discharging the contents of the float chamber into the conduit leading to the head-piecero'l' the compressor, and continue operating, drawing the water from the float chamber, until the float, in its falling, impinges upon the lower set of floatarms. The float-arms actuate the Valve-arms and the valve, closing the port connecting the atmosphere and the float chamber and re-establishing connection between the float chamber and the vacuum chamber. The air, at atmospheric pressure, rushes from the float chamber into the vacuum chamber and the water therein imn'iediately falls to the same elevation as that or the float chamber. The

flap-valve on the throat of the vacuum con.

nection falls, a vacuum is thereafter quickly established in both the vacuum and float chambers and the process '01 filling begins again. It is thus seen that by the alternate rise anl tall ot' the float, actuating the automatic valve, conditions are established which result in the alternate filling and emptying oi the vacuum and float chambers, and in the supply to the head-piece of the compressor of water raised to an elevation above that (if the tidal elevation. of the fore-bay.

It is apparent that, when an open connection exists between the vacuum chamber of LO return into the float cl amber. The free openings of the pipes in the roofs of the vacuum and floatchan'ibers are hooded above the ceiling of the chambers, thereby insuring againstwater rising to and covering said pipes. he air supply pipe from the atmosphere is valved for the purpose of regulating the access of air to the float 'clum1ber,'such regulation determining the speed and periodicity of operation of the water elevating apparatus. r

The compressor head is directly connected with the discharge channel leading from the siphon-drait-tubes, and consists of a vertically regulatable upper portion carrying a multiple of air tubes, suspended above the where the air is released, the air freed water rising through the Lip-take pipe and escaping through the gates of the taihrace either to the sea or to the estuary;

But an apparatus as above described would be mechanically impossible and inoperative without an extraneous source of energy, the source of energy employed being some form of fuel, burned either directly in a pre-heater for the sole and only purpose of increasing the power value of the compressed air delivered from the hydraulic compressor, by heating the same, or, by the use of waste heat for heating the air secured from a coal reduction or metallurgical process carried on in connection with the tidal power plant. It is a well known principle of mechanics that air expands readily under the influence of heat, and, due to its being a perfect and without latent heating qualities, all, or nearly all of the heat units absorbed by the air in its preliminary and intermediate beatings ca be recovered in useful work. Because of this principleit becomes possible to elevate the water to a super-elevation above the tidal crest and to use this elevation in conjunction with a slight diil'erence in the elevation 01 the tide within and without the dam. and, after accounting iior the power expended in securing such super-elevation to obtain a large residue of commercial power.

In this linking of a hydraulic compressor to an air expansion apparatus the following is the procedure employed. A force main leads from the separation chamber to a preheaterin which either waste heat or fuel is employed to heat the air, the air entering at a point of relative minor. temperature and after passing through the pre-heater in areverse direction to that of the fuel gases, is discharged at a point of maximum temper ature. It immediately enters the initial cylinder of a multiple expansion engine, either of a reciprocating or turbine type, where -a partial expansion of the air ensues and a considerable drop in temperature results. From'this initial, or-from an intermediate expansion, theexhaust is lead to a freezer, for the purpose of freezing out any moisture in the expanded air before final expansion to a pressure below atmosphere, as such expan sion results in a very low temperature and one which would quickly congeal any residual moisture remaining in the .air,and freeze up the engine ports. The agency employed in freezing out this residual-moisture is the exhaust from the terminal expansion cylinder, said exhaust being circulated through coils enclosedjinafreezer, around the exterior of said coils and within the shell ofthe freezer, the exhaust from the initial and intermediate cylinders circulate, saidcontact resulting in the freezing out and dep osition of the residual moisture upon the ex terior of the coils. The exhaust ofthe initial or intermediatecylinder,-being freed of itsmoisture, returns to the source of heat, first passing through the coils of an interchanger which isflsurrou'nded by a1r at atmospheric temperature so'that' the exhaust air is raised to said atmospheric temperature beforeentrance to the regenerator, whichis an extensionof the flue of the waste heat orpre heater source of energy, and in which regenerator the exhaust air is againheatedto approximately thetemperature of the initial pre-heat. From the regenerator; the air. passes finally to the terminal expansion cylinder in which it is expanded to a, pressure below atmosphere and to that represented by the vacuum desired to be secured in the vacuum chamber of the water elevatingap paratus; This low. pressure exhaust after passing through the freezerand being used to freeze out the moisture from the partially expanded air, enters a vacuum tank to which is likewise connected the vacuum pipe leading to the vacuum chamber of the water elevat'ing apparatus, and which is also connected to the supply pipe of a vacuum pump. This vacuumpump maintains the vacuum in the vacuum tanln An automaticvalve controls the pressure of the vacuum tank to that desired for the operation of the water elevating apparatus. It is apparent that by linking up the water elevating apparatus and the air expansion engine it is possible to secure the super-elevation of the'tidal water and to ex.- haust the'air below atmosphere, the resulting economy being very high.

The following great advantages are se-i cured by the use. of a combined hydraulic compressor operating underan augmented fall secured through the super-elevation of the tidal crest-and a compressedair expansion unit, in; which the-,airifinally. exhausted in vacuuo, issubjected toinitial pre-heat and intermediate regeneration, with moisture elimination. Itis possible to. begin the operationof the compressor very-inuch sooner. after the tidal. turning, resulting in being able to operate continuously for much of the tidal period,o r' from to of that time. The compressor always works under a constant head andnot under a variable, as is theusualcondition. It is possible to secure as commercialpower nearly .1 O()% of the power representedin the tidal, flow, and fiuctuation, after. allowing for the cost of fuel consumed, which fuel costs may be nothing, as in the case of waste heat. installations or, if fuel is. consumed for. thepurpose of heatingthe; airf not over one-quarter the cost of thefuel consumed in; steam-power production. A large amount ofthe power devel ,opedby the. tidalcompressor may be stored.

as compressedair inthe separation chamber, and drawn upon. and used during periods when the compressor, at t dal turning points,

is e sar lyi operat ve,

For the satisfactory operationlofJthe pow; er plant as above describedit isessential that av body of air shall be present in'the' ,separa;

tion chamben to supply air ,to the expansion engine n order to produce the vacuum nec essary to the operation of the waterg elevating ppa t scha odye e lf' th senem-q tion chamberv is secured by means :ofan initial.

compressor, which is in all essentials similar; to the compressors heretofore described, ex-; p th t t has a; xe ce np e ea i steadof a floating, A separate, and ,comparatively small fore-bay witligates onoppositef sides, supplies water to thecompressor, either from the-seaor from the estuarys The head is regulatable, although not floating, and, by an adjustment of the gates, can be successfully, if, not economically operated through such a period as isnecessary in order to store. a suliicient amount of air in the separation chamber with which, to beginoperating the con'ipressedair engine, after which, the initial compressor is shut down andfurther compression takes place'through the main, or floating compressors. Y e I r Thistidal compressor isprotectedin allits parts soas toproof against either pressures above or below thelimits prescribed, a, re guev latingvalve being located upon the-force;

main, which valve closesat a point of mini I CIl level in the separation chamber, and discharges air into the atmosphere when this lowest water elevation is reached.

One desirable feature in the operation of a hydraulic compressor, either tidal or otherwise, is the maintenance of a practically constant elevation of the tail race. Fluctuations in this tail-race elevation, such as that induced by heavy wave action fromthe sea ward side when the compressor is discharging into the sea, would produce sudden variations in pressure which might injure the plant. To prevent such wave fluctuations, or at least to reduce them, a wave barrier'is introduced on the seaward side, with openings therein, so disposed as to dissipate the waves, and prevent their reaching the tail-race and seriously affecting the elevation of the Water therein.

hat I claim is 1. Ina tidalhydraulic air compressor, a fore-bay basin, a tail-race basin, a clowntake shaft located in said fore-bay basin, an uptake shaft located in said tail-race basin, a head-piece supported upon and located above the Water insaid fore-baybasin, means for elevating water from said fore-bay basin, means connecting said water elevating means and said head-plece, means connecting said head-piece and said down-take shaft and means connecting said clown-take shaft and said uptake shaf 2. In a tidal hydraulic air compressor, a

fore-bay basin, walls surrounding said basin,

gates in said walls connecting said basin with a tidal estuary, other gates connecting said basin With the sea, a tail-race basin, walls surrounding said basin, gates in said Walls connecting said basin with a tidal estuary, other gates connecting said basin with the sea, a doWn-take shaft located in saidforebay basin, an uptake shaft located in said tailrace basin, a head-piece supported upon and located above the water in said fore-bay basin, means for elevating Water from said forebay basin, means connecting said water elevating means and said head-piece, means connecting said head-piece and said down-take shaft and means connecting said downtake shaft and said up-take shaft. 7

3. In a tidal hydraulic air compressor, the combination of a fore-bay basin, pontoons-in said basin, head-pieces supported by said pontoons, downtake shafts, means connecting said head-pieces and said shafts, an up take shaft, a separation chamber connecting said downtake and uptake shafts, means for elevating water from said 'forebay, means connecting said head-pieces and said water elevating means, a supplementary downtake shaft, a fixed head-piece superimposed'above said downtake shaft and separate means connesting said supplementary downtake pipe and said separation chamber. I I

l. Ina hydraulic air compressor, a forebay basin, a head-plece, a down-take shaft,

meansconnecting said head-piece and said down-take shaft, an up-take shaft, means con necting said down-take shaft and said up-take shaft, means for elevating water from said fore-bay basin, means connecting said head piece and said water elevating means and means for producing a vacuum within said water elevating means.

5. In a hydraulic air compressor, a fore-bay basin, a head-piece, a down-take shaft, means connecting said head-piece and said downtake shaft, an up-take shaft, a separation chamber connecting said down-take shaft and said rip-take shaft, means for elevating water from said fore-bay basin, means connecting said headpiece and said water elevating means, an initial compressing unit and means connecting said initial compressing unit and said separation chamber.

6. In a tidal hydraulic air compressor, a head-piece, a water elevating means, means connecting said headpiece and said water elevating means, a fore-bay basin, a downtake shaft located in said fore-bay basin, means connecting said head-piece and said down-take shaft, a tail-race basin, an uptake shaft located in said tail-race basin, means connecting said down-take shaft and said up-take shaft, walls surrounding said tail-race basin, gates in said Walls anda WELVG protection wall in front of said gates.

7. In a tidal hydraulic air compressor, a head-piece, a Water elevating means, means connecting said head-piece and said water elevating means, a fore-bay basin, a downtakeshaft located in said fore-bay basin, means connecting said headpiece and said down ta ke shaft, a tail-race basin, an up-take shaft located in said tail-race basin, means connecting said down-take shaft and said uptake shaft, walls surrounding said tail-race basin, gates in said walls, a wave protection Wall in front of said gates and openings in said protection wall.

8. Ina hydraulic air compressor, a forebay basin, ahead-piece, water elevating means, means connecting said head-piece and said elevating means and a pontoon floating in said fore-bay and supporting said headpiece and said elevating means.

9. In a hydraulic air compressor, a water elevating apparatus, a vacuum chamber in said apparatus, a fore-bay basin, supply pipes connecting said chamber and said basin, valves in said pipes, a float chamber, a part1- tion between said vacuum chamber and said float chamber, a sealed opening in said partiv V 1) valves protecting said connecting means, an

outer shell to said float chamber, a discharge conduit and means connecting said chamber and said conduit and passing through said elevating apparatus, a vacuum chamber in said apparatus, a Water supply basin, supply pipes connecting said chamber and said basin, a float chamber, a partition between said vacuum chamber and said float chamber, a sealed openingin said partition, a float, an automatic valve, means actuated'by said float and operating said valve, connections through said. valve between said float chamber and the atmosphere and between said float chamber and said vacuum chamber, a source 01 vacuum,

means connecting said vacuum chamber and said source, a discharge conduit and means connecting said float chamber and said discharge conduit.

11. In a tidal hydraulic air compressor, the

combination of an initial compressing unit, a fore-bay basin, walls surrounding said basin, gates in said Walls connecting said basin with the sea, other gates in said Walls connecting said basin With a tidal estuary, a,

water elevating apparatus, means for producmg a vacuum in said apparatus, a headpiece, means connecting said Water elea vating apparatus and said head-piece, a

down-take shaft, means connecting said,

head-piece and said down-take shaft, a sepdoWn-take shaft and said separation chamher, a tail-race basin, an up-take shaft discharging into said tail-race basin, means connecting said separation chamber and said uptake shaft, walls surrounding said tail-race basin, gates in said Walls connecting said basin with the sea, other gates in said Walls connecting said basin With a tidal estuary, means connecting said initial compressing unit and said separation chamber and a force main connected to said separation chamber.

Signed at New York, in the county of New York and State oi'Ne-W York, this 6th day of October A. D., 1921.

HERBERT M. KNIGHT.

aration chamber, means connecting said 7 

